1. Field of the Invention
The present invention relates to a method and apparatus for recording and reproducing data onto and from an optical recording medium, and more particularly to a method and apparatus for recording and reproducing data onto and from an optical recording medium using a zigzag scan, wherein data contained in a data sector are scanned in the zigzag manner, the zigzag scanned data are recorded on the optical recording medium and the recorded data are reproduced from the optical recording medium.
2. Description of the Background Art
Recently, an optical recording medium and an optical magnetic recording medium, which are capable of recording a large quantity of information such as video and audio data, have been developed for practical use.
The optical recording mediums are classified into a reproduction-only recording medium such as a compact disk (CD), a CD-Read Only Memory (CD-ROM) and a digital versatile disk-ROM (DVD-ROM); a WORM (Write Once Read Memory) type recording medium such as a CD-R (CD-Recordable) and a DVD-R (DVD-Recordable); and a rewritable recording medium such as a CD-RW (CD-Rewritable) and a DVD-RAM (DVD-Random Access Memory).
Data is recorded in a different format according to the type of the optical recording medium. For example, a data format recorded in the recordable optical recording medium such as the DVD-RAM will now be described.
In order to record data on the recordable optical recording medium, a user data is processed as a data sector, a record sector and a physical sector.
The data sector having the size of 2064 byte includes a main data part in which 2048 byte data is recorded and a 16 byte ID record part in which sector information or the like is recorded. The user data is recorded in the main data part.
The record sector is generated as the data recorded in the main data part is scrambled and an error correction code is added.
The physical sector is generated as the record sector is modulated in an eight to fourteen modulation (EFM) plus method and a synchronous signal is added to the modulated data.
In the EFM plus method, the current 8 bit data is modulated to a 16 bit data according to a previous state. Accordingly, the data of the physical sector generated finally after the user data is processed according to the above-described method is recorded in the recordable optical recording medium. This will now be described in more detail.
FIG. 1 is a drawing illustrating the construction of a data sector in accordance with a conventional art.
As shown in FIG. 1, the data sector includes 12 rows of a main data part, and an ID record part consisting of 12 bytes at the starting portion of the first row of the main data part and 4 bytes at the ending portion of the 12th row of the main data part.
Each row of the main data part includes 172 bytes. Since the first row includes the 12 byte ID record part, the main data part is 160 byte, and since the 12th row includes the 4 byte ID record part, the main data part is 168 byte.
A 4 byte data ID (Identification), a 2 byte IDE (ID Error detection code), a 6 byte RSV (Reverse) and a 4 byte EDC (Error Detection Code) are recorded in the ID record part.
Information such as the sector number, a sector layer or area is recorded in the data ID. A parity bit for detecting an error in the data ID is recorded in the IDE. Information such as copy prevention information is recorded in the RSV. A parity bit for detecting an error of the whole sector is recorded in the EDC.
The user data is recorded in the 2048 byte main data. The record sector with the above described structure is generated as the data is scrambled and an error correction code is added thereto.
FIG. 2 is a drawing illustrating a record sector in accordance with the conventional art. As shown in FIG. 2, the record sector has 13 rows and each row has 182 bytes. An error correction code (ECC) is inserted for the 10 byte of the end portion of each row. Accordingly, the record sector is modulated, for example, using an EFM plus method, and when a synchronous signal is added to the modulated data, a physical sector as shown in FIG. 3 is generated.
FIG. 3 is a drawing illustrating a physical sector in accordance with the conventional art.
As shown in FIG. 3, the physical sector has 13 rows and each row has 2976 bytes. The physical sector is generated as the record sector is modulated by the EFM plus method and a 4 byte synchronous signal (SY) is added for every 1456 byte of the modulated data.
The EFM plus modulation is performed to reduce a high frequency component of a record pulse and to restrain a DC component.
The 4 byte synchronous signal (SY) is inserted for every 182 byte of the EFM plus modulated data. Thus, two synchronous signals (SY) are inserted in each row consisting of 372 bytes.
The data of the generated physical sector is NRZI (Non Return to Zero Inversion) converted and sequentially recorded in the recordable optical recording medium, as indicated in a dotted row.
FIG. 4 is a drawing illustrating an apparatus of recording and reproducing data to and from the optical recording medium in accordance with the conventional art.
As shown in FIG. 4, the apparatus for recording and reproducing data to and from the optical recording medium includes a scramble and ECC adding unit 4 receiving a data sector, scrambling it, adding an error correction signal and generating a record sector, a modulator 6 receiving the record sector and EFM-plus-modulating the record sector, a synchronous signal inserting unit 8 receiving the EFM plus modulated data, inserting a synchronous signal thereto and generating a physical sector, and a recording unit 12 receiving the physical sector from the synchronous signal inserting unit 8 and recording it on an optical recording medium.
The operation of the apparatus of FIG. 4 will now be explained.
In a recording mode:
When an image data as a main data and a data sector containing an ID record part of a data desired to be recorded in an optical recording medium are inputted to the scramble and ECC adding unit 4, the scramble and ECC adding unit 4 scrambles the inputted data sector, inserts an error correction code thereto and generates a record sector.
When the record data is inputted from the scramble and ECC adding unit 4 to the modulator 6, the modulator 6 performs the EFM plus process on the record sector.
When the EFM plus modulated data is inputted from the modulator 6 to the synchronous signal inserting unit 8, the synchronous signal inserting unit 8 inserts a synchronous signal into the EFM plus modulated data and generates a physical sector.
In a reproducing mode:
The data recorded on the optical recording medium in the recording mode, as discussed above, is reproduced by a reproducing unit.
However, as indicated in a dotted row in FIG. 3, the data of the physical sector is sequentially recorded on the recordable optical recording medium. Thus, as shown in FIG. 5, if there is a scratch 2 in the same direction as the tracks of the optical recording medium, the data recorded on the optical recording medium inevitably contains a bust error when being reproduced (the bust error may be generated when a data recorded on an optical recording medium contaminated with dust or a fingerprint is reproduced).
At this time, an error correction code is inserted in order to correct the error of the data being reproduced. But since it can correct a limited number of errors, failing to correct such a scratch results in the data recorded on the optical recording medium to be reproduced incompletely. That is, the above method and apparatus for recording and reproducing data to and from the optical recording medium have a problem that the data recorded on the optical recording medium having scratches formed in the same direction as the track direction will have errors or will be incompletely reproduced.